Regarding installation separations closer than the test separation. The RE limit is based on protecting some level of signal-to-noise ratio at the victim broadcast receiver from interference at some assumed level of received broadcast signal level. If that level of rfi has been measured at three meters from a test article, then as you move in closer the rfi field intensity will increase, but you don't know how much because you are in the near field. The victim snr will suffer, but you don't know how much, and it only matters if the broadcast signal level is at or below that assumed when setting the limit.
> From: John Woodgate <[email protected]> > Date: Thu, 28 Jun 2007 08:08:23 +0100 > To: [email protected] > Subject: Re: Internal Margins for Emissions Testing > > In message <c2a88b41.586d4%[email protected]>, dated Wed, 27 > Jun 2007, Ken Javor <[email protected]> writes: > >> As Mr. Woodgate pointed out earlier in this thread, if you put things >> closer together than the separation distance at which they were >> qualified, all bets are off. > > Well, not quite, because there is, or is alleged to be, a 'secret' > margin built in there, too. But it doesn't allow for separations of > approximately 1 m or less. > > In some cases, there is enough information available from various > sources to calculate the separation distance at which reception of a > given radio signal is intolerably impaired. > -- > OOO - Own Opinions Only. Try www.jmwa.demon.co.uk and www.isce.org.uk > There are benefits from being irrational - just ask the square root of 2. > John Woodgate, J M Woodgate and Associates, Rayleigh, Essex UK > > - > ---------------------------------------------------------------- > This message is from the IEEE Product Safety Engineering Society > emc-pstc discussion list. Website: http://www.ieee-pses.org/ > > To post a message to the list, send your e-mail to [email protected] > > Instructions: http://listserv.ieee.org/request/user-guide.html > > List rules: http://www.ieee-pses.org/listrules.html > > For help, send mail to the list administrators: > > Scott Douglas [email protected] > Mike Cantwell [email protected] > > For policy questions, send mail to: > > Jim Bacher: [email protected] > David Heald: [email protected] > > All emc-pstc postings are archived and searchable on the web at: > > http://www.ieeecommunities.org/emc-pstc - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. Website: http://www.ieee-pses.org/ To post a message to the list, send your e-mail to [email protected] Instructions: http://listserv.ieee.org/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas [email protected] Mike Cantwell [email protected] For policy questions, send mail to: Jim Bacher: [email protected] David Heald: [email protected] All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc ______________________________________________________________________ This email has been scanned by the MessageLabs Email Security System. For more information please visit http://www.messagelabs.com/email ______________________________________________________________________
